1. Field of the Invention
This invention relates to a bed apparatus used in support of image diagnosis, such as X-ray CT.
2. Description of the Related Art
A bed apparatus used with an image diagnosis apparatus, such as X-ray CT, is generally composed of a tabletop 10 on which a patient (person to be examined) may lie, and a bed 20 that is a base for supporting the tabletop 10 and a device for driving it, as shown in FIG. 1. The tabletop 10 may be fitted with attachments, such as a headrest and an armrest (as shown by dotted lines in FIG. 1). The tabletop 10 is constructed to be horizontally and reciprocally movable along the axis of the body of the person to be examined (along the arrow Z shown in FIG. 1) by a driving device installed in the bed 20.
The tabletop 10 is also constructed so that it can be fitted at its end facing the photographing apparatus with attachments, such as a headrest for supporting the head of the person to be examined and an armrest for supporting his arms. The attachments, such as the headrest and armrest, are fitted in various places, depending on the photographing method that is employed. Arrangements employed in the related art for fitting such attachments are shown by way of example in FIGS. 2 to 4. At its end facing the photographing apparatus, the tabletop 10 has a connecting hole 10a through which the attachments, such as the headrest and armrest, may be connected. At its top, the tabletop 10 has metallic fixing pins 10b for fixing the attachments to the tabletop 10, flexible straps 10c for connecting the fixing pins 10b to the tabletop 10 and fixing holes 10d in which the fixing pins 10b can be inserted for fixing the attachments.
As shown in FIG. 2, the headrest is a supporting device of small thickness for supporting the head of the person to be examined so that it's photographing may be carried out satisfactorily. The headrest 30 can be connected with the tabletop 10 if its connecting portion 30a is inserted into the connecting hole 10a of the tabletop 10. The headrest 30 has fixing holes 30b in its connecting portion 30a, so that if the metallic fixing pins 10b connected to the top of the tabletop 10 by the straps 10c are inserted in its fixing holes 10d provided on the top of the tabletop 10 after the headrest is connected with the tabletop 10, the fixing pins 10b may pass through the fixing holes 30b to fix the headrest to the tabletop 10.
The armrest is used to support the upper arm portions of the person to be examined in the vicinity of his head so that his arms do not obstruct the photographing of the upper half of his body. FIG. 3 is a partly cutaway view of a conventional armrest. The armrest 40 can be connected with the tabletop 10 if its connecting portion 40a is inserted into the connecting hole 10a of the tabletop 10. The armrest 40 has fixing holes 40b in its connecting portion 40a, so that if the fixing pins 10b connected to the top of the tabletop 10 by the straps 10c are inserted in its fixing holes 10d provided on the top of the tabletop 10 after the connecting portion 40a is connected with the tabletop 10, the fixing pins 10b may pass through the fixing holes 40b to fix the armrest to the tabletop 10.
Conventional attachments, however, have a variety of problems as will now be explained. The series of operations associated with connecting and fixing an attachment, such as headrest 30 or armrest 40, to the tabletop 10 are troublesome, since they consist of two steps: (a) inserting the connecting portion of the attachment into the connecting hole 10a of the tabletop 10; and then (b) inserting the fixing pins 10b situated above the tabletop 10 into the fixing holes 10d in the top of the tabletop 10. The conventional armrest 40 is constructed so that its connection to the tabletop 10 is possible only after the removal of the headrest 30. The process of removal and fitting is troublesome. Moreover, the presence of two fixing pins 10b in the conventional system makes it difficult for one person to complete the removal process, since it is necessary to draw out the attachment while drawing up the two pins.
Another drawback of the conventional system relates to differences in the effective range of photographing between when the armrest 40 is used, and when the headrest 30 is used, as shown in FIGS. 4A and 4B. When the armrest 40 is used, the person P to be examined lies with the top of his head situated substantially at one end of the tabletop 10 as shown in FIG. 4A. But when the headrest 30 is used, the person P lies with his head protruding beyond that end of the tabletop 10 as shown in FIG. 4B. However, the conventional tabletop 10 is supported at only one end and must be supported by the bed 20 along at least one end portion having a length x, irrespective of the position of the person to be examined on the tabletop. Therefore, the effective range of photographing varies whether the headrest is used and thus requires the person to be examined to lie with his head shifted on the tabletop.
In FIGS. 4A and 4B, a CT apparatus is shown as an example of a conventional photographing apparatus. The CT contains an X-ray tube (X) and a detector (D) that dictate a photographing position I. The oblique lines employed for a portion of the tabletop 10 in FIG. 4A or 4B denote where the attachment, such as headrest 30 or armrest 40, is connected to the tabletop 10. That portion defines a low-count region, since its connecting parts (such as the fixing pins 10c) are metallic and tend to produce a low-count artifact. The fact that the metallic parts narrow the effective range of photographing as mentioned impedes and inconveniences photographing.
What is required, as discovered by the present inventors is an attachment, such as a headrest or an armrest that does not impedes photographing or requires patients to be repositioned as extremities are photographed.